Allow for sig chain to be disabled.

Tools like dex2oat or patchoat don't need the sig chain or the fault
manager. This also enables building a statically link version of
dex2oat.

Change-Id: I9897728cac48acade854bb027bfde860628ebf84
diff --git a/runtime/runtime_options.def b/runtime/runtime_options.def
index fc527b5..d5f7f97 100644
--- a/runtime/runtime_options.def
+++ b/runtime/runtime_options.def
@@ -91,6 +91,7 @@
 RUNTIME_OPTIONS_KEY (BackgroundGcOption,  BackgroundGc)
 
 RUNTIME_OPTIONS_KEY (Unit,                DisableExplicitGC)
+RUNTIME_OPTIONS_KEY (Unit,                NoSigChain)
 RUNTIME_OPTIONS_KEY (LogVerbosity,        Verbose)
 RUNTIME_OPTIONS_KEY (unsigned int,        LockProfThreshold)
 RUNTIME_OPTIONS_KEY (std::string,         StackTraceFile)